The effects of benzene inhalation on murine hematopoietic precursor cells (CFU-e, BFU-e and CFU-gm).

Male B6D2F1 mice were exposed by inhalation to 4000 ppm of benzene for 8 h/day for 1, 2, 3, 5, 7 or 14 days and then sacrificed at 18 h following the last exposure. The cellularities of both femur and spleen were depressed for the duration of benzene exposure. BFU-e/femur declined for 3 days, rebounded to control levels by day 5, and were again depressed by day 7. CFU-e/femur were initially depressed, but by day 7, the concentrations of CFU-e were so elevated that the total number had actually rebounded to slightly higher than control values. CFU-gm/femur remained depressed for the duration of the exposure periods. CFU-e, BFU-e and CFU-gm/spleen were depressed following all exposures. The toxic effects of benzene on hematopoiesis that are immediate are not ascribable to migration of stem cells between femur and spleen. The depressive effects of benzene inhalation on erythropoiesis may be compensated by the rapid proliferation of CFU-e.